

#include<bits/stdc++.h>

using namespace std;

int fib(int n) {
    if (n == 1 || n == 2)return 1;
    else return fib(n - 1) + fib(n - 2);
}


int main() {
    long long start = clock();//Mac/Linux  纳秒 vs windows平台下是毫秒
    fib(50);
    long long end = clock();
    cout << (end - start) / CLOCKS_PER_SEC << endl;
    return 0;
}